Data transmission is an important part of many integrated circuits and systems having integrated circuits. Data is typically communicated with an integrated circuit by way on an input/output (I/O) port. Data may be communicated in a system in different formats and according to a variety data communication protocols. However, the input/output circuits can significantly affect the performance of an integrated circuit device. Accordingly, I/O ports are often monitored to determine performance characteristics of the I/O port, and therefore the integrated circuit device and possibly a system implementing the integrated circuit device.
Conventional integrated circuits implement process monitor vehicle (PMV) circuits to monitor input/output (I/O) transistor process corners. However, the PMV circuits are not true representation of I/O circuits because of their structure, causing difficulties of correlation between the PMV results and I/O performance. Also, I/O performance tests and product tests usually involve fabric circuits, making it hard to isolate and characterize the true IO performance. In some cases, the delay contribution from FPGA fabric for example can be significant. For example, the delay can be up to 50%. In conventional devices, a typical configuration for I/O performance characterization applies an input signal to an I/O pad, through a Rx buffer and input multiplexer, and then to the fabric. The signal is then routed back from fabric to a transmitter through an output multiplexer to another I/O pad to be observed. In this configuration, circuits from both IO and fabric impact the signal, making it hard to isolate the contributions of delay, jitter and duty cycle distortion of the fabric from I/O circuit.